diff --git a/src/claim.js b/src/claim.js
index 081e88c..ab5c030 100644
--- a/src/claim.js
+++ b/src/claim.js
@@ -251,7 +251,7 @@ class Claim {
 
         // Post process the data
         const def = claimDefinitions.data[claimData.serviceprovider.name]
-        if (def.functions && def.functions.postprocess) {
+        if (def.functions?.postprocess) {
           try {
             ({ claimData, proofData } = def.functions.postprocess(claimData, proofData))
           } catch (_) {}
diff --git a/src/fetcher/telegram.js b/src/fetcher/telegram.js
index eac1b4c..7130f6a 100644
--- a/src/fetcher/telegram.js
+++ b/src/fetcher/telegram.js
@@ -54,7 +54,7 @@ module.exports.fn = async (data, opts) => {
       throw new Error(`Telegram fetcher was not set up properly (${err.message})`)
     }
 
-    if (!data.chat || !data.user) {
+    if (!(data.chat && data.user)) {
       reject(new Error('Both chat name and user name must be provided'))
       return
     }
diff --git a/src/keys.js b/src/keys.js
index 5fcdba3..bb62e4a 100644
--- a/src/keys.js
+++ b/src/keys.js
@@ -260,7 +260,7 @@ const fetch = async (identifier) => {
  * });
  */
 const process = async (publicKey) => {
-  if (!publicKey || !(publicKey instanceof openpgp.PublicKey)) {
+  if (!(publicKey && (publicKey instanceof openpgp.PublicKey))) {
     throw new Error('Invalid public key')
   }
 
diff --git a/src/verifications.js b/src/verifications.js
index 5059ab1..c92a900 100644
--- a/src/verifications.js
+++ b/src/verifications.js
@@ -93,7 +93,6 @@ const containsProof = async (data, fingerprint, claimFormat) => {
           break
 
         default:
-          continue
       }
     }
   }
diff --git a/test/keys.test.js b/test/keys.test.js
index eb52bd4..b6884c2 100644
--- a/test/keys.test.js
+++ b/test/keys.test.js
@@ -21,8 +21,8 @@ const path = require('path')
 const openpgp = require('openpgp')
 const doipjs = require('../src')
 
-const pubKeyFingerprint = `3637202523e7c1309ab79e99ef2dc5827b445f4b`
-const pubKeyEmail = `test@doip.rocks`
+const pubKeyFingerprint = "3637202523e7c1309ab79e99ef2dc5827b445f4b"
+const pubKeyEmail = "test@doip.rocks"
 
 const pubKeyPlaintext = `-----BEGIN PGP PUBLIC KEY BLOCK-----